18 Ohau River

Access: Take SH57, the Shannon Road to Palmerston North, along Kimberley and Arapaepae Rds then swing R along Tararua Rd to Gladstone Rd. The Ohau Pipe Bridge is 5.9 kilometres from the Arapaepae-Tararua Rd intersection; it is the second bridge across the Ohau and carries prominent notices. Light vehicles may be taken over this bridge to a small carpark at the end of Poads Road, 1.2 km beyond.

Overview: The Ohau Valley, in addition to a couple of lesser headwaters, has one major sidestream, the Blackwater Stream. Blackwater Junction is the name adopted here for the area around the confluence of the two rivers.

The Ohau is gorgy over much of its length, and most of the travel is in the streambed. This catchment was one of the most severely damaged in the 1936 storm, but off-track travel is no longer so difficult — at least, not for that reason.

The routes to the Ohau Valley and Waiopehu Hut start at the end of Poads Rd. At the DOC display board is an intentions book to be filled in. This entrance crosses private land over which an access agreement has been negotiated. Dogs must be on a lead and firearms unloaded when on private property. [revised March 2017]

18.1 Ohau road-end to Blackwater Junction QFG

A stock-proof gate on the L leads behind a barn and down to a route marked by blue poles across a paddock to a stile alongside a gate. Across the stile, marker poles lead to a culverted stream. Keep to the high terrace here. At the far end, another stile crosses the fenceline at the Park boundary.

This bush-edge stile marks the junction of three routes. Across the steps is the track to the Blackwater Junction and beyond; and 75 metres along this, the track to Waiopehu Hut branches off uphill. On the grass terrace below the steps, another stile crosses the fence to an old road. This leads to the river and can be used if one travels to or from Blackwater Junction by way of the river, rather than the track. This takes about an hour longer than the track, but as only one or two of the river crossings (almost) require a swim, provides a pleasant alternative in summer's heat. Going downstream, pine trees seen on the TR indicate you are nearing the exit point

Inside the Park boundary, the track is fairly level and well defined and crosses three minor creeks before crossing Blackwater Stream on a suspension bridge. One minute past this lies a high grass terrace; the Ohau River is reached a couple of minutes further on. From the carpark to Blackwater Junction, a good hour. Blackwater Stream itself may be reached from the TL of the Blackwater bridge.

Blackwater Junction vicinity. From Blackwater Junction, tracks go up to the Waiopehu Ridge and the Gable End Ridge. Riverbed travel takes you up the Ohau River to South Ohau Hut and beyond, passing the north branch of the Ohau River and Deception Spur on the way. [revised March 2017]

18.2 Waiopehu Hut and Waiopehu QFG

Close to 5 hours from road-end to hut, 25 minutes from hut to Waiopehu.

Seventy-five metres inside the bush from the Park boundary steps, the track to Waiopehu climbs steeply for a few minutes to gain the spur-crest, then somewhat more gently thereafter. The branch track coming directly from the Blackwater Junction is passed after 50 minutes, and 30 minutes further brings a stream crossing. This was the site of an old track-work camp – 75 m along the spurlet on the TR. A good hour from the track-work stream brings the site of the now vanished Edwards Shelter.

Beyond here the ridge undulates through the forest to reach an open clearing on the spur, the site of two previous huts, in about 80 min. The earliest hut was blown off the ridge in the 1936 storm, and its replacement was snuggled in the ridge-side hollow. A fringe of bush gives way to healthy scrub, and a good 30 min brings the new Waiopehu Hut. This light and spacious new hut sleeps 20 comfortably, and is about (Topo50 BN33 991 890, NZMS260 S25 091 507). Like other unheated huts above bushline, it may be cold in some seasons.

From Waiopehu Hut a fringe of bush gives way to scrubby tussock and the top of Waiopehu in 25 minutes. This fine viewpoint gives excellent views of the Northern Tararuas and the Horowhenua and is well worth the climb. The track sidles the actual summit of Waiopehu, and just beyond the top a flat area on the right with a tarn marks the junction of the Oriwa Ridge. [An old Māori trail traversed Waiopehu and this tarn may well have been Pehu's water.] From Waiopehu’s summit, choose your short-cut back to the sidle with care. [revised November 2017]

18.3 Waiopehu Hut to Te Matawai Hut QOT

From Waiopehu poles mark the route to Twin Peak, with its memorial trig, and a deepish saddle leads to Richards Knob, a good hour from Waiopehu Hut. (From here the Gable End Ridge leads to Blackwater Junction, an important escape route from Te Matawai if the rivers are too high.)

Beyond Richards Knob the track leads down through the bush of Butcher Saddle, 50 minutes distant; then a 25-minute climb to knoll 810 on the Ohau – Te Matawai Track.

Forty minutes from this junction brings the huge helicopter clearing just before Te Matawai Hut. This hut sleeps about 20, has water tanks and a toilet.

18.4 Blackwater Junction to South Ohau Hut QOT

Forty minutes river travel to the Junction of the north and south branches of the Ohau, and 80 minutes further to the hut. In heavy rain the river quickly becomes impassable, and the route out from the tops is via Butcher Saddle and down Gable End Ridge, or (longer) via Waiopehu.

Note. An earthquake in 2003 damaged the terrace upon which South Ohau Hut squatted, the hut was removed and replaced by a new (2008) 10 bunk hut.

Beyond Blackwater Junction the track continues over terraces for a few minutes to emerge on a bouldery beach. Note this entry point for the return journey. From here to the junction of the North Ohau, travel is up the stream-bed with several crossings, a few of which are swift even in moderate water. At night and by torchlight, it has been known for parties to travel up the North Ohau rather than the South.

On the TL, 'Aussies Track' bypasses this river section and takes about the same time, but it is fairly rough going and may suffer from rockfall in the forseeable future. It starts at the Blackwater Junction just above the terrace-edge 40 metres beyond the Gable End turn-off, but is not well marked. It emerges on the TL, about 25 metres downstream of the junction with the North Branch. A small extension of it goes as far as the first flats (żColenso Flat) in the South Ohau above the Junction.

From the Junction, a short gorge in the South Ohau is passed almost immediately, then 30 minutes of easy river travel gives way to 30 minutes of bouldery gorge travel. Once past a small stream from the TR the going becomes easier for the final 20 minutes to South Ohau Hut site: 2 hours from Blackwater Junction. Sleeps 12, water from the stream, has a toilet.

18.5 North Branch, Ohau River QOT

From the confluence of North and South Ohau (40 minutes from Blackwater Junction), a short gorge section – one waist-deep pool – leads to somewhat easier going in the North Ohau and to the North Ohau Hut (Topo50 BN33 033 930) in 75 minutes. The upper reaches and eastern faces of this stream were seriously damaged by the 1936 storm, but while some lower slopes remain scrubby, tree-growth has rendered many spurs passable again. [revised February 2018]

18.6 Deception Spur to Avalanche Flats QBN

Inwards: Deception Spur lies between the North and South branches of the Ohau, 40 minutes above Blackwater Junction. This spur is nowadays a route only, though it was a common track before the 1936 storm. Quite rough as far as .357, the spur thereafter is currently well cleared, passing a couple of minor saddles before emerging on the main ridge near .865. About 2˝ hours. (A used route to the North Ohau Hut starts 500 metres ENE along the ridge.) [revised February 2019]

From here to Avalanche Flats it is perhaps best to travel SE along the ridge until 200 metres past a small open slip on the R, from where a NE spur provides good going right to the Mangahao Valley, just above the old Avalanche Flats Hut site. About 4 hours from the Ohau junction. The new Mangahao Flats Hut is downstream a good 50 minutes on the TR at (Topo50 BN34 059 926, NZMS260 S25 159 543). But Avalanche Flats is always a nice camping spot.

The remainder of this ridge-crest gives simple OT travel to Girdlestone Saddle. The slip mentioned is on an active extension of the Otaki – Mangahao fault-line and, in the bush and streams on the Mangahao side to the NE, it creates some small bluffs and waterfalls.

In early days, a Northern Crossing route used to travel up the Ohau and Deception Spur; climb to Dundas from the Mangahao; and from here one could travel over Bannister or Mitre. On the occasion of an early trip, a large bush avalanche on the TL gave Avalanche Flats its name.

Outwards: On the outward journey, this spur is picked up on the TL of the Mangahao, upstream of a tiny creek, just up from the old Avalanche Flats hut site. Deception Spur is marked at its top by a cairn and discs; it will provide no problem to those adequately versed in bushcraft.

The stream lying S of Deception Spur can reward those deprived of adventure.

18.7 Gable End Ridge QOT

This is a most important escape route from the Northern Tararuas in wet weather. About 2˝–3 hours from Richards Knob to Blackwater Junction.

Up: Starting just beyond the high grass terrace at Blackwater Junction, this track heads steeply up a small rocky step to the bushed spur, which moderates after 20 minutes or so. Beyond this it rises steadily over Mayo Knob to exit the bush-edge just before Gable End, about 2˝ hours from Blackwater Junction. Beyond Gable End the track is essentially in the open tussock and scrub, and reaches Richards Knob in another hour. There are fine views en route of North Ohau River and of the tops of the Northern Tararuas.

Down: Richards Knob, about 50 minutes from Butcher Saddle, is not far above the bush-edge, and the track junction is obvious. The track is well padded though a little obscured by long grass at times, and travels over a couple of knobs to reach Gable End and the bush beyond: about an hour from Richards Knob. The track then drops through the bush, past a longish flat section and over bushed Mayo Knob, followed by a steeper drop down to Blackwater Junction. Like many tracks in this area, it can be seriously muddy. [revised January 2016]

18.8 Blackwater Junction – Waiopehu Hut QOT

This is an untracked route only, which provides an agreeable summer approach to Waiopehu Hut. Travel is initially up the stream-bed, and Waiopehu Hut will be reached in 4–5 hours depending upon the river experience of the party and its size. There is one minor waterfall but no gorge and the stream travel should be no trouble.

From the TL of the Blackwater bridge a trail will be found leading upstream for 100 metres to the Blackwater itself. About 2 hours will find you in the small stream just E of Bush Corner on the Waiopehu Track. Near (Topo50 BN33 990 903, NZMS260 S25 090 520) is a small waterfall, easily scrambled up, and a few minutes upstream of this is a steep re-vegetating slip on the TL. Climb this and the bush spur beyond to gain the Waiopehu Track about 15 minutes below the old hut site.

18.9 Blackwater Junction to Poads Road-end QFG

Outwards: The track from Blackwater Junction to the road-end first leads up the Blackwater valley to cross the suspension bridge. Between here and the farmland it passes three small streams and is well padded. At the bush-edge steps, follow the marked route across the paddocks and below the barn to the gate at the road-end. One hour from Blackwater Junction to the farmhouse is good going.

A most pleasant alternative to the track on a fine day is to travel down the river to the farmland. This route takes rather longer and there are one or two minor swims en route. Gain the river either from the end of the track just beyond the high grass terrace, or via the steep track upstream of the TL of the Blackwater bridge. The exit at the Ohau (Levin) water intake is obvious and leads up the concrete steps to the grass flats just by the bush-edge stile. Take care not to pollute the water supply and keep clear of the intake structure. [revised March 2017]

18.10 Blackwater Junction to Waiopehu Ridge QOT

From the TL of the Blackwater bridge, this trail climbs almost immediately to reach the Waiopehu Ridge in an hour, about 15 minutes short of the camp stream. This route is labelled the "6-disc track". [revised March 2017]

South Ohau Hut vicinity

18.11 South Ohau Hut to Te Matawai Hut via Girdlestone Saddle QOT

About 2˝hours. Note. An earthquake in 2003 damaged the terrace upon which South Ohau Hut sat, and the hut was temporarily removed.

Up: From South Ohau Hut, proceed up the eastern headwater. Keep R at the first significant fork and L at the next one, some 30 minutes from the hut. Both forks are cairned. Twenty-five metres beyond this second fork, the Dowling Falls by-pass track climbs 40 metres on the TL to a spur, which it follows for a few minutes before dropping steeply to the stream again. At the next fork turn L and, 15 minutes upstream, a small and almost dry gut joins from the TL. A cairn here marks the start of the steeply climbing route, poorly marked, that reaches Girdlestone Saddle in 15 minutes, some 90 minutes or so from the South Ohau Hut.

From the fork 30 minutes above South Ohau Hut, one may travel upstream for a visit to Dowling Falls. Another branch is passed before the falls. An older route sidled the falls somewhat more immediately on their TL.

To Te Matawai Hut, the good uphill track heads SSW from Girdlestone Saddle, and in less than 1 hour the small knob will be reached where it joins the track running from Te Matawai to Pukematawai. Turn R down into the scrub, and Te Matawai Hut should be reached 75 minutes from Girdlestone Saddle.

Down: Twenty minutes towards Pukematawai from the hut is the Girdlestone Saddle turn-off, and the well-marked and gently padded track drops to Girdlestone Saddle 50 minutes from the hut. The saddle is clearly marked by a DOC sign. The track branching SE to the Mangahao is well cut, but that heading NW to the South Ohau is only lightly defined.

The South Ohau headwater stream is reached 10 minutes from the saddle and opens out somewhat in another 10 minutes. A tiny stream joins from the TL and, almost immediately, cairns on the TL mark the start of the sidle that thoroughly by-passes Dowling Falls. A spur is gained some 20 metres up, and this is followed to eventually regain stream level in 20 minutes, about 25 metres upstream of a major fork. The two notches on the bypass spur mark the crossing of recent Otaki – Mangahao Fault traces. These faults are possibly connected to the origins of Dowling Falls lying to your R and more falls up the stream branch to your L.

Twenty-five minutes below these forks and down a short gorge, South Ohau Hut is reached, perched on its high terrace, some 75 minutes from Girdlestone Saddle.

18.12 South Ohau Hut to Te Matawai Hut via Yeates Track QOT

The 'Yeates 600' (feet) is the abrupt climb behind South Ohau Hut where the trail climbs steeply for 35 minutes before suddenly easing off. The spur turns R and rises more gently for the remainder of the Yeates Track to meet the track from Butcher Saddle at point 810, about 75 minutes from South Ohau Hut. Te Matawai Hut is about 35 minutes from this junction, just beyond the huge helicopter clearing. This hut sleeps 20 or more. About 2 hours in total.

For the route beyond this to the Northern or Bannister Crossings, see Major Crossings, 20.6.

Emergency exit. Gable End Ridge or Waiopehu Ridge are both good alternatives to a flooded Ohau River. At present Aussies Track, from Ohau Forks to Blackwater Junction, offers a route on the TL but this may be subject to rockfall. See 18.4.

18.13 South Ohau Hut to Butcher Saddle QOT

This route to Butcher Saddle offers practice in sidling waterfalls. Fifteen minutes from South Ohau Hut up the easy terraces of Butcher Creek brings an obvious fork. Take the L stream and after 25 minutes of quick easy height, the first waterfall comes into view. The first two or three falls are simply passed, but their successors become more troublesome and continuous. Intermittent deer trails offer a sidle about 50 metres above the stream on the TL and, once beyond the second small streamlet, the upper basin is regained just before the final pull to the saddle.

From here one may drop into the upper Otaki in 30 minutes; and the best sidling of these falls is on the TR.